I have to think in terms of durability. In it's worst form, 1970's 350 sbc smog motors will run for 200k miles. Not many engines can be built and modified for less money. The later Buick 3.8/3800 engines would last for 300k. I have heard stories of the big Ford six and Rambler six running forever. All of those engines have run at Indy.

The original poster referenced using 90% of it's main parts available to the masses, i.e heads, blocks, rods, crankshafts and intakes. I'm still going with G3 Hemi. The Hellcat engine is available in crate form and it's a mass produced powerplant that belts out over 700hp. How can one pull that off with the ancient technology of a BBC using 90% of it's main parts?

Easy.. I have dozens of big block chevys making well north of that in street trim. Heck you can bolt together 900hp in natural aspiration pump gas.

Simple build would be a 10.5:1 632 spread ports and single 1450 dominator. If you can't make 1000hp with that. Choose a different hobby.
That's 300 more than your reference

Ok, ok.
When you said "fairly simple" and use "most of the stock parts", fast NA V8.... the first thing that came to mind was CHRYSLER
20 years ago, I think that would be the right answer, but that's changed. What was it....roller cams? but there must be other factors.

Yeah the BBC chevy heads are DARN good design. You probably are right. Good heads and a good enough block and it's big.
What you need such a big engine for anyway?

One would expect anything, not just a car engine, to be a 'vastly superior design' to something of 50 years prior. Just compare your mobile phone or TV set to what was on offer 50 years ago.

The 426 Hemi was a winner from day one, literally. Cobbled together quickly in 7 months to debut at the 1964 Daytona 500 & beat the Ferds, it surprised many by not only finishing it's inaugural race, but grabbing the 1st four places!!!!!!

another rare engine was the ford semi hemi got slammed in most racing venues because of its powers.
just after purchasing my 69 Shelby GT350 the boss 429s hit the show room floor. told my sales guy wanted to trade in my 2 month old shelby for it he thought i was joking. gave me all kinds of excuses as to why he couldnt sell it to me

The boss 429 is a BBC killer.

You might consider a hopped up, 427 L-88 or 454 LS-7 engine here too. both approaching 550 and 600 hp in full house trim! Heck, maybe more?? Drop either one into a lightweight 1st Gen. Camaro built for the strip and have more fun than John Law will allow! Or like the, "Big Red 1", '69 Camaro for actual driving.

another rare engine was the ford semi hemi got slammed in most racing venues because of its powers.
just after purchasing my 69 Shelby GT350 the boss 429s hit the show room floor. told my sales guy wanted to trade in my 2 month old shelby for it he thought i was joking. gave me all kinds of excuses as to why he couldnt sell it to me

The Boss 429s never hit the showroom here, and I went to buy one after seeing the center fold ad for them. They had never even heard of it, and had no interest in selling one. So I went and bought a new L78

And I didn't know it at the time, but I could have went into my local Ford Dealer in town and ordered a 427 Cobra! I was single and working on the Railroad right out of HS so could have afforded one!

The original poster referenced using 90% of it's main parts available to the masses, i.e heads, blocks, rods, crankshafts and intakes. I'm still going with G3 Hemi. The Hellcat engine is available in crate form and it's a mass produced powerplant that belts out over 700hp. How can one pull that off with the ancient technology of a BBC using 90% of it's main parts?

Probably just by working the BBC's heads over, adding a decent carb. and intake manifold, a good set of 4-tube, long tube headers and one old school UDHarold solid flat tappet lifter cams.

I am thinking that Harold might have been getting 800 hp out of a good 454?? Maybe it was the late John Lingenfelter, or Mark Jones/VortecPro?

Sticking with the criteria that you have to use 90% of the oem main components, actually todays small blocks are really good and hold their own. The 427 LS7 can be competitive. Especially the 6.4 392 Hemi. They arguably have the best cylinder heads ever offered in a oem small block reaching 400 cfm ported. Add cam, compression and drag pack intake and 750 hp shouldn't be hard pressed. Big block or small, hemi covers them all. Lol

If overall hp per ci is concerned, with OEM heads and block, the Coyote has the most potential.

For most everyone else, their choice is an emotional argument. Nothing wrong with that, but let’s recognize that for what it is. For those of us who weren’t around then and don’t have a nostalgia for a certain time period, I fail to see the allure of a lot of these engines in OEM trim which the the OP was asking about.

. The 426 Hemi was a winner from day one, literally. Cobbled together quickly in 7 months to debut at the 1964 Daytona 500 & beat the Ferds, it surprised many by not only finishing it's inaugural race, but grabbing the 1st four places!!!!!!

How many engines can you think of that did that???

Like technology, engine knowledge has matured and rule makers are a lot better of establishing parity. For a Chrysler, it was right place at the right time and caught the naivety of the rule makers off guard.

This is what I was hoping for with this thread. Keep it up . Anyhow, I have worked on them all, so, I have a unique perspective. Believe me, I am well aware of what a hemi mopar can do. But, still, .100 over 454 4 bolt block, gm steel crank with some slugs in it for internal balance, that's 470 inches, throw in some main studs, and maybe a little block filler, and that block will handle a lot of power. 990 rectangle ports, with a good port job, angle mill, dowel shift, big valve etc, can flow 385-390 cfm. One of the other factors, cost. Its hard to beat. That pretty much throws the hemi out the window. As far as the coyote, yes, they are impressive. But, again, they are 302 inches. It aint hanging. Horsepower/inch, sure it wins, but that's not what I am talking about. Ls7's, another cool engine, but even with all that technology, that dinosaur still will make more power.